var isNav4, isNav, isIE;
if (parseInt(navigator.appVersion.charAt(0)) >= 4) {
  isNav = (navigator.appName=="Netscape") ? true : false;
  isIE = (navigator.appName.indexOf("Microsoft") != -1) ? true : false;
}
if (navigator.appName=="Netscape") {
	isNav4 = (parseInt(navigator.appVersion.charAt(0))==4);
}